Camilla, a fan of the show, specifically requested the trip to the film set - a rundown car scrapyard in the middle of nowhere where detectives are looking for a boy who may be a witness - as part of her tour of Scandinavia.

Sofie, who plays lead detective Sarah Lund, said: "I think it is really surreal. But it's lovely that she wanted to come here.

"I told her last night to wear flat shoes. This is not really an inviting place for a royal visit."

The series creator, writer Soren Sveistrup, who met the couple yesterday at a reception hosted by the British ambassador, said:

"Royalty is not the kind of audience you would expect. Prince Charles told me that it was Camilla who introduced him to The Killing.

"He said it was one of the only things they could agree on seeing together."